Gravity
by ash the airbender
Summary: He burned so bright and fast that, like a star too massive to hold up against gravity, he collapsed in on himself and snuffed out while John kept burning. (Johnlock one-shot)


**Gravity**

XXX

_A/N: Sherlock may have deleted most of his knowledge of astronomy from his mental hard drive, but I have not. The subject fascinates me, particularly the life cycles of stars. So please forgive this science-y one-shot, it's more to get me back in the groove of writing than anything else._

_Told from John's perspective, so for all intents and purposes, Sherlock and Moriarty are dead. Please inform me of any grammar or spelling mistakes._

XXX

A star lives its whole life fighting the relentless inward pull of gravity. The need for a force to counteract this endless pull is why a star burns: it flourishes not despite the forces seeking to destroy it, but because of them. Sherlock Holmes was like this. He was a massive supergiant of a star that burned so bright and fast he lit up the sky with all his radiance.

Stars burn because they have to. Without the fiery heat and energy of thermonuclear fusion canceling out the force of a star's own gravity, a star would collapse in on itself. This collapse can, on the one hand, end in a gradual, unremarkable fading, but it can also cause some of the greatest, brightest explosions in the universe.

From the start, Sherlock Holmes was always doomed to face the latter.

XXX

The oldest stars in the universe are also the dimmest: the red dwarves that can burn slowly and steadily on for trillions of years, older than the universe itself. These stars escape mostly unnoticed by gravity, lingering on the edges of their galaxies, barely blips on the radar of existence, keeping to themselves and carrying on despite the catastrophic changes occurring around them every minute.

John is unremarkable, a long-lasting star that burns dimly for eons, unchanging, and that should be enough for him. But somehow it isn't. Because he's always so near to the action, close enough to watch the swiftly burning stars in all their bright and brilliant glory, close enough to wish he could be like them, wise enough to realize that this brighter way of living cannot sustain itself for very long before collapse.

He's close enough to watch the brilliant destruction of a brilliant man, but far enough away to be powerless to stop it.

XXX

A star starts out burning hydrogen into helium, and when this finite supply of hydrogen is depleted in the star's core, the star enters the next stage of its life. This is a shorter, less stable stage, burning helium into carbon and oxygen. It doesn't last long enough to serve as much more than a temporary, false sense of security, a fragile Plan B that was never as good as Plan A in the first place. It's just to hold the gravity at bay.

The night at the pool, Sherlock realized he was out of hydrogen in his core. And for a minute it seemed he would die then and there, in a spectacular flash of light and heat and sound (_there is no sound in space, but there was in the pool that night, though John could barely hear it over the pounding blood and panic in his ear_). The supernova would have taken John and Moriarty out in its wake.

But that didn't happen. Moriarty's attentions were diverted elsewhere, for a while, and John and Sherlock were lulled into believing the helium would somehow last.

XXX

Once a star's supply of helium runs out, it can take one of two paths: either the star shrinks down to an ultra-dense white dwarf, fending off gravity with the energy leftover from its life, or, if a star is hot enough and massive enough, it continues fusing elements further along the periodic table. Rapidly, the star burns through elements in order, each lasting less than the one before, until it reaches iron.

Sherlock was burning through the elements like wildfire in the time after the incident at the pool. He knew his time was running out – John suspects, in his heart, he knew it all along as well – but there was nothing he could do, nowhere to go but forward, spinning helplessly on his axis as the clock ticked seconds off his life. Time waits for no man.

When a star has burned its core to iron, it can go no further. Without enough energy from fusion, the star has no choice but to yield. Gravity, the vengeful force that has been waiting and watching as this arrogant star that dared defy it runs its lifeclock down to zero, takes over. The star collapses on itself, and the same mass that kept it burning so long turns against it, crashing inward, building pressure, building density, until…

Boom.

XXX

The candles of the universe, supernovae are as beautiful as they are deadly. Moriarty could not escape the explosion; he was too near. He burnt up with Sherlock and they spiraled out of existence together, just as Moriarty would have always wanted it, for one could not survive without the other. Every action has an equal and opposite reaction.

Was Sherlock the action or the reaction?

XXX

John may have escaped the supernova's blast, but he often wishes he hadn't. To die would have been easier, easier than this. Easier than living without Sherlock, living a life that is, for lack of a better word, _boring_.

It would have been better if he'd never met Sherlock in the first place. He was shown a better way of living, a faster, more exciting way. His life was boring before, but it hadn't mattered, because he hadn't known what he was missing.

Now he knows. He knows what he's missing, without Sherlock in his life, and he knows, but that's not even the worst of it.

XXX

It took Sherlock dying for John to realize. Seeing the man standing on the ledge, feeling his heart pulse rapidly in his chest; the world slowed down around him, slowed to a crawl, and John knew why he'd killed a man for Sherlock, ran with him, been willing to die for him. He hadn't known it at the time, when he'd done all those things, but he knows it now, and it was true all along.

Sherlock didn't have friends. He just had John. And John wasn't so sure what they had was friendship… not at the end. John might have been imagining it, but he thinks, at some point, whatever it was between them developed into something more.

But it was too late then, and it's too late now, sitting in the dark in the planetarium where they'd chased the Golem, listening to a disembodied voice narrate the life of a star, thinking about his small, dim self against the former radiant brilliance of Sherlock.

XXX

Gravity. It holds things together, but in the end, it tears them apart. There's no escaping it, not forever, only temporary ways to hold it back long enough to say your goodbyes, the goodbyes you didn't know mattered until it was too late to say everything you know you needed to.

And then you collapse. You yield to gravity.

You fall.


End file.
